How to create a Matplotlib bar chart with a threshold line?

To create a Matplotlib bar chart with a threshold line, we have to use axhline() method.


  • Set the figure size and adjust the padding between and around the subplots.
  • Initialize a variable, threshold.
  • Make lists for bars values.
  • Get the below and above bar values based on the threshold value.
  • Create a figure and a set of subplots using subplots() method.
  • Plot bars with x, a_threshold and b_threshold values.
  • Add a horizontal line across the axis using axhline() method.
  • To display the figure, use show() method.


import numpy as np
import matplotlib.pyplot as plt

plt.rcParams["figure.figsize"] = [7.50, 3.50]
plt.rcParams["figure.autolayout"] = True
threshold = 10
values = np.array([8.0, 10.0, 15.0, 9.0, 12.0])
x = range(len(values))

a_threshold = np.maximum(values - threshold, 0)
b_threshold = np.minimum(values, threshold)

fig, ax = plt.subplots(), b_threshold, 0.35, color="blue"), a_threshold, 0.35, color="yellow", bottom=b_threshold)

plt.axhline(threshold, color='red', ls='dotted')


Updated on: 03-Jun-2021

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